This invention concerns drinking vessels and more particularly drinking vessels designed to keep a chilled beverage cold during the period when the beverage is being consumed by a user of the vessel. Insulated jackets have been used in the past, but in seeking further improvements in keeping the beverage cold, beverage vessels have been provided with a surrounding space filled with a xe2x80x9crefrigerant gelxe2x80x9d. The vessel is kept in a refrigerator or freezer to chill the gel prior to use. When a cooled beverage is poured into the vessel, the gel acts to absorb heat from the beverage to maintain its cold condition over an extended period of time.
U.S. Pat. No. 5,001,907 describes such a vessel comprising a mug having a large handle which keeps the fingers from contacting the cold walls of the vessel, and insuring a secure grip.
Heretofore, this xe2x80x9cstay coolxe2x80x9d design has not been employed in drinking vessels other than mugs due to the unpleasantness associated with directly grasping the outer wall of a drinking vessel which is chilled by such refrigerant gel. Also, body heat conducted through the fingers when the vessel walls directly grip the vessel would tend to warm the beverage. The outer wall would also be slippery and hard to handle securely when the grasped surfaces are chilled.
It is the object of the present invention to provide a drinking vessel which has a xe2x80x9cstay coolxe2x80x9d outer wall which may be directly and securely gripped by a user without discomfort despite its low temperature condition, and which minimizes warming of the liquid by body heat.
This object and others which will become apparent upon a reading of the following specification and claims are achieved by providing a series of widely spaced ribs projecting radially from the exterior perimeter wall defining a cavity containing the refrigerant gel. The ribs eliminates the discomfort otherwise experienced when the gel is chilled to keep the vessel""s contents cool, and also reduces the transfer of heat from the holder""s hand into the vessel.
In addition, the ribs enable a more secure gripping of the vessel.
The vessel is preferably constructed by nesting an inner transparent plastic beverage container piece into a plastic outer holder piece formed with the exterior ribs, and fixing the same together as by ultrasonic welding. The exterior of the beverage container piece and the interior of the holder piece are offset to define an annular cavity receiving the refrigerant gel.